st: probit "backed up"

Dear all,
I'm having problems with a simple probit not converging---the output says "backed up" after 4-5 iterations. Im using Medical Expenditure Panel Survey from 1996-2010 (about 217,000 observations) and running a probit on the probability of being privately insured (private (0,1) as the dependent variable). The explanatory variables include a number of dummy variables, but even if I limit the list to only a few dummy and continuous variables (family size, age, male, black, employed), it still won't converge. Any suggestions on what else to try? Im using Stata 12.
Thank you,
Helen
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